1. Field of the Invention
This invention generally relates to communication devices. More particularly, the invention relates to devices that provide full-duplex communication and to devices that provide remote control of personal computers.
2. Description of the Related Art
It is well-known that, in full-duplex communications operations such as normal telephone conversations, it is important to either physically separate an audio input device from audio output as much as possible or to provide an earpiece so that a lower output volume level can be used, as in the conventional telephone handset. This prevents acoustic feedback from being conducted by the structure of the housing.
Also, in full-duplex communications operations that do not use an earpiece, it is important to control the phase and directional relationships between audio input and audio output transducers, the speaker and the microphone, to prevent the sort of feedback that produces the squeals heard from improperly-used public address systems.
Conventional audio transducers for multimedia computers are mounted together below the computer monitor screen inside the screen enclosure, or in a separate audio enclosure resting on top of the screen enclosure, with the microphone between two speakers. All three transducer apertures are aligned on a flat surface facing the operator. Thus the conventional, screen-mounted microphone is subjected to structural conduction and will receive acoustic feedback that varies in phase and volume depending on the nature of the reflective surface opposite those speakers and its distance from the microphone, as is well known.
In particular, feedback is readily conducted by the respective enclosure because of the close proximity of these transducers to each other. Speaker sound is also readily reflected by opposing surfaces with little attenuation because of the speakers' proximity to the microphone and because all apertures in these units face in the same direction. Moreover the placement of the three audio transducer apertures in the flat, vertical front face of a conventional enclosure does nothing to shield the input transducer from such reflections.
Mounting a microphone on the computer screen enclosure in this conventional way is particularly problematic when computer voice command control is in use. Feedback and noise interfere with productivity in voice-command computer control operations because they reduce the accuracy of the computer's command recognition operations, thus reducing its speed.
Efficient voice communication, and voice-command computer control in particular, has three principal requirements:
1) A constant distance between the microphone and the person speaking, preferably a close proximity.
2) Shielding of the microphone from other voices and other extraneous noise.
3) Feedback prevention.
The first requirement assures an adequate input volume level. This level decreases rapidly as this person moves away, in accordance with the inverse-squares' law. Locating the microphone in close proximity to the person speaking also assures the best possible signal-to-noise ratio for accurate voice recognition. However, conventional computer audio equipment meets this requirement by immobilizing the operators in front of the computer screen when they use voice-command computer control, chaining them to their chairs. This, in itself, interferes with the workstation's productivity.
The second requirement is simply ignored in the design of the conventional computer audio inputs noted above. Mounting the microphone on a flat surface above or below the computer screen, provides little or no shielding from either ambient noise or reflected speaker sound.
The third requirement is often met by providing only half-duplex audio communication, speaker-phones' artificial alternation between providing audio output and accepting audio input. In human communication, this is disruptive and annoying.
Apart from voice recognition problems, operator efficiency is also hindered by lack of inter-modal coordination and flexibility. Real-time on-line communications activity, in general, is increasing rapidly. The computers themselves have become digital communications hubs connected by modem to telephone lines for facsimile transmissions, electronic mail and information exchanges between data banks. They are also increasingly used to access multimedia resources and process audio and video inputs.
Computers are no longer just off-line number-crunching or wordprocessing appliances. Nor is the operator dependent upon an alphanumeric keyboard and CRT for control of and responses from the computer. However, the complex interaction of these new functions demands more spatial and modal flexibility for the computer operator. In particular, an improved audio link is needed to prevent the attendant increases in functional complexity from interfering with workstation productivity.
For example, computer operators are hindered when their computer work is interrupted by telephone calls. They must locate the ringing telephone, perhaps digging it out from beneath the working papers accumulating on the desk, and pick up its handset to answer the call. This diverts them from the computer screen. "Hands-free" telephone equipment may simplify that process, but half-duplex speaker-phone operations interfere with normal conversation and people who are not employed full-time as telephone operators find headsets annoying.
Moreover, voice synthesis can completely free computer operators from their dependence on the CRT for monitoring the computer's operations, but conventional voice-command hardware immobilizes them in front of that CRT. This new, additional lack of mobility interferes with the operators' access to the physical resources available to them just as surely as the old CRT and keyboard interface did. This severely limits the potential usefulness of voice synthesis in computer control operations.
For these reasons, the conventional voice-communications system provided for personal computers is merely a toy. When productivity is at issue, these well-known shortcomings of the conventional computer audio hardware are intolerable.